1. Field of the Invention
The present invention relates to a positioning structure for a frame and brackets in a modular-type wiper device that is to be mounted on a vehicle, such as a passenger car, bus, or truck.
2. Description of Related Art
Conventionally, such a modular-type wiper device has been formed by die forming and integrating a first bracket to which the wiper motor is attached with a second bracket to which the wiper shaft is attached. However, in view of the recent strict demand for reduction in weight, the present applicant has proposed, for example, in Japanese Application for Utility Model Registration No. 2-115569, a structure in which a reduction in weight and size is attained by integrally connecting the first and second brackets by a cylindrical tubular member. In this proposed structure, the first and second brackets are fastened to the end portions of the tubular member by means of bolts. A problem with this structure is that it requires blind nuts, which are rather expensive, on the side of the tubular member. Moreover, such blind nuts must be in conformity with the inner configuration of the tubular member, so that it is necessary to prepare different blind nuts for different inner frame configurations, resulting in poor versatility.
In view of this, a structure has been proposed in which a channel-type frame having a substantially U-shaped cross-section is used and the brackets are fastened thereto by means of general-purpose bolts and nuts. In such a structure, the relative positioning between the frame and the brackets at the time of fastening by bolts and nuts has been conducted by utilizing the bolt holes provided in the frame and the brackets. However, in the case of an automated bolt fastening process, the frame and the brackets are set in position on an assembly jig and, in this condition, the automatic bolt fastening is conducted. Thus, it is impossible to perform the above-mentioned relative positioning between the frame and the brackets by utilizing the bolt holes. To perform this relative positioning, it would be necessary to provide the assembly jig with members for positioning the frame and the brackets, resulting in an increase in the size of the assembly jig. Even then, some measure would have to be taken to achieve an improvement in operational efficiency so as to facilitate the setting of the frame and the brackets on the assembly jig. This might be achieved by enlarging the play at the time of setting. However, that would involve a deterioration in the accuracy of the relative positioning between the frame and the brackets. If the frame and the brackets were fastened to each other in that condition, various problems would be involved, such as a dispersion in the wiping range of the wiper arm. To avoid this, some other measure must be taken to effect the positioning between the frame and the brackets with a still higher level of accuracy.